Zig-Zag
量化系数的Z行排序。为了保证低频分量先出现，高频分量后出现，以增加行程中连续“0”的个数，这63元素采用了“之”字型（Zig-Zag）的排序方法。
标准顺序定义如下：
static int Zig_Zag[8][8]={
{0,1,5,6,14,15,27,28},
{2,4,7,13,16,26,29,42},
{3,8,12,17,25,30,41,43},
{9,11,18,24,31,40,44,53},
{10,19,23,32,39,45,52,54},
{20,22,33,38,46,51,55,60},
{21,34,37,47,50,56,59,61},
{35,36,48,49,57,58,62,63}
};
公式：ZIG(3,PER)